Impact fuzes for explosive projectiles including a mechanical self-destruction device



Feb. 3, 1959 A MECHANICAL SELF-DESTRUCTION DEVICE Filed May 17. 1956 2 Sheets-Sheet 1 w. GUERNE 2,871,788 IMPACT FUZES FOR EXPLOSIVE PROJECTILES mcwomc Feb. 3, 1959 w. GUERNE 2,871,788

- IMPACT FUZES FOR EXPLOSI-VE PROJECTILES INCLUDING A MECHANICAL SELF-DESTRUCTION DEVICE Filed May 17, 1956 I 2' Sheets-Sheet 2 FOR EXPLOSIVE PROJECTILES MECHANICAL SELF-DESTRUC- IMPACT FUZES INCLUDING A TION DEVICE William Guerne, Geneva,

Aero-Mecaniques S. A., Geneva, Switzerland, a society of Switzerland shells (of a caliber ranging from 20 to 50 mm.) for anti-aircraft automatic guns, said fuzes being intended to be mounted on projectiles having a movement of rotation about their axis and which include a self-destruction device including at least one centrifugal locking member kept in locking position as long as the speed of rotation of the projectile-about its axis remains above a predetermined value, said locking member temporarily holding in waiting position an intermediate member capable, when released and under the action of a resilient system, of setting off the fuze by displacement of a movbale part which is generally a firing pin.

The object of my invention is to provide a fuze of this kind which is better adapted to meet the requirements of practice than those used up to this time, and in particular which works always in the same fashion irrespective of the value of the impact shock (provided of course this shock is sufiicient) For this purpose, according to my invention, I provide, in the front portion of the fuze body, a push-piece operative by an impact shock and mounted to act directly, through its displacement caused by said shock, on said locking member so as to produce the retraction thereof and consequently the release of the intermediate member which then communicates to the movable part (firing pin), under the only action 'of the resilient system (that is to say irrespective of the violence of .the impact shock), a displacement which sets off the fuze.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

Fig. 1 is an axial section .view of an impact fuze made according to my invention, said fuze being shown in the state of rest, that is to say such as it is before the projectile is fired.

Figs. 2 and 3 are half-sections showing the positions of the parts of this fuze at two different times during the operation thereof.

Inside .an ogive-shaped fuze body 1 there is provided an axial cylindrical hole 2 in which is slidable axially a first sleeve 3 the rear part of which is surrounded by a spring ring 4 the rear edge of which bears against a shoulder 5 provided in said sleeve 3, said ring 4 and shoulder 5 being located in an enlarged hole 6 in line with the hole 2 at the rear thereof.

Sleeve 3 is provided, rearwardly' of shoulder 5, with a transverse cylindrical housing 7 in which are slidably guided two cylindrical masses 8 the outer ends of which are of frusto-conical shape.

A second sleeve 9 is slidable axially in the first sleeve 3 and it is provided with radial housings 10 each of which contains a centrifugal mass constituted by a ball 11 which, 'in its position at the maximum distance from the axis of the fuze body, is applied against the bevelshaped edge 3a of sleeve 3, this front edge 3a therefore acting as a frusto-conical cam. Sleeve 9 forms a hous- Switzerland, assignor to Brevets 2,871,788 Patented Feb. 3, 1959 ice ing for a spring 12 surrounding a firing pin 13. The rear end of said spring 12 is applied against a shoulder 9a integral with sleeve 9. The front end of spring 12 is applied against a piece 18 applied frontwardly against a shoulder of the fuze body 1 and Which will be more explicitly referred to hereinafter.

In the position of rest, the elements of this fuze occupy the positions indicated by Fig. l. Sleeve 3 is kept in its rear position by spring ring 4 and the firing pin 13 is held in fixed position .because its collar or its shoulder 14 is applied against the two masses 8 which are themselves held in a housing having oblique walls 15 provided in a threaded plug 16 fixed on the rear portion of the fuze body I. Said plug 16 is provided with another housing 17 intended to receive the detonator which may for instance be of the delay type.

Before describing the essential feature of my invention it seems preferable, for the sake of clarity, to explain how the system above described will operate when the shell is fired.

As soon as said shell leaves the gun and under the efiect of the centrifugal forces created by the rotation of said shell, the balls 11 are applied against the bevelshaped front edge 3a of sleeve 3, thus temporarily preventing any possibility'of rearward movement of the inner sleeve 9 with respect to sleeve 3. On the other hand, said centrifugal forces cause ring 4 to expand (thus releasing sleeve 3) and masses 8 to -move radially in the outward direction. Said masses, by reaction against inclined walls 15, pushfrontwardly the whole of sleeves 3 and 9 and firing pin 13. Finally, the external, sleeve 3 is locked in its forward position by masses 8 which are at the maximum distance from each other and which then release the enlarged portion 14. of the firing pin 13, the inner sleeve 9 being held in its forward position by balls 11. n

The fuze is then ready to he set upon an obstacle, by percussion means 'Which will be explained hereinafter and the various partsof said fuze occupy the positions illustrated by Fig. 2.

off, in oase of impact If no obstacle is struck by the shell, automatic destruction thereof will.take place at the time the centrifugal force acting upon the balls 11 is no longer sulficient to balance the action of. spring 12. This spring will first compel balls 11 to retract in their housings 10, then it will push. the inner sleeve 9 thus released and the firing pin 13 toward the primer of the detonator, thus operating the fuze and causing destruction of the shell.

Up to the present time, in order to ensure operation of the fuze in case of an impact of the shell upon an obstacle, the firing pin was directly exposed to the impact shock. The drawback of such an arrangement is that the percussion effect is depend nt upon theviolence of said shock, which does not permit ofdetermining'in advance, when the fuze is being manufactured, the optimum conditions of percussion and in particular the force with which the firing pin is to strike the primer of the detonator.

The object of that this violence exceeds a predetermined minimum.

According to my invention, I provide in the front portion of the body 1 of the fuze a push-piece 18 exposed acts directly upon the for retracting them into sleeve 9 when there is an Impact of the shell upon an obstacle. Advantageously, said push-piece is protected within certain limits by a relatively thin disc 19 capable of resisting slight shocks of a violence lower than the minimum violence under which the fuze is to operate.

In order to enable push-piece 18 to retract the balls 11 into sleeve 9 when there is an impact of the shell upon an obstacle, it suifices to give the rear end of said pushpiece the shape of a sleeve the rear edge of which 18a is frusto-conical so that said rear edge can, when pushpiece 18 is driven rearwardly into the fuze body, compel balls 11 to retract into their respective housings 10.

Fig. 3 shows the positions occupied by the elements of the fuze just at the time impact occurs, that is to say when push-piece 18 has caused balls 11 to retract into the housing .and the whole of sleeve 9 and firing pin 13 is going to-be driven rearwardly by spring 12, as indicated by arrow F.

It will be seen that, with such .a construction, the importance of the impact shock has no influence upon the operation of the fuze and this result is obtained merely by the addition to a self-destruction mechanical device of the above described type, of a supplementary part, to wit push-piece 18.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eificient embodiments of my invention, it should be Well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. An impact fuze for use with a rotating projectile which comprises, in combination, a fuze body having a longitudinal axis, a member movable longitudinally in said body, an impact responsive push-piece slidable longitudinally in said body, cooperating abutment means carried by said fuze body and said push-piece, said push-piece being initially fitted in said fuze body in the position where said abutment means are in contact together, whereby said push-piece can slide longitudinally from said position only in one direction, resilient means interposed between said push-piece and said member for urging said member in said direction with respect to said push-piece, a firing part movable in said body from an inactive position to a firing position in which the fuze is set ofli, said firing part being operatively connected with said member so that longitudinal movement of said member in said direction under the action of said resilient means causes said firing part to move from said inactive position to said firing position, at least one centrifugal mass guided in said member so as to be movable transversely thereto between an outward position and a retracted position, abutment means carried .by said fuze body adapted to cooperate with said centrifugal mass in outward position to prevent said member from moving in said direction under the action of said resilient means, whereas said centrifugal mass in retracted position is clear of said last mentioned abutment means which then does not prevent said member from moving in said direction, and cam means carried by said push-piece to engage said centrifl, ugal mass and move it into retracted position when said push-piece is moved in said direction in said fuze body by the efiect of impact.

2. An impact fuze for use with a rotating projectile which comprises, in combination, a fuze body having a longitudinal axis, a sleeve movable longitudinally in said body, an impact responsive push-piece slidable longitudinally in said body, cooperating abutment means carried by said fuze body and said push-piece, said pushpiece being initially fitted in said fuze body in the position where said abutment means are in contact together, whereby said push-piece can slide longitudinally from said position only in the rearward direction, a spring interposed between push-piece and said sleeve for urging said sleeve in said direction with respect to said pushpiece, a firing pin slidable in said sleeve from a forward inactive position to a rearward firing position in which the fuze is set off, said firing pin including a shoulder in contact with the rear face of said sleeve so that longitudinal movement of said sleeve in the rearward direction under the action of said spring causes said firing pin to move from said inactive position to said firing position, at least one centrifugal mass guided in-said sleeve so as to be movable transversely thereto between an outward position and a retracted position, abutment means carried by said fuze body adapted to cooperate with said centrifugal mass in outward position to prevent said sleeve from moving in the rearward direction under the action of said spring, whereas said centrifugal mass in retracted position is clear of said last mentioned abutment means which then do not prevent said sleeve from moving in the rearward direction, and cam means carried by said push-piece to engage said centrifugal mass and move it into retracted position when said push-piece is moved in the rearward direction in said fuzebody by the efiect of impact.

3. An impact fuze according to claim 2 in which said sleeve is provided with radial cylindrical guiding passages, said centrifugal mass being inthe form of balls movably guided in said cylindrical passages.

4. An impact fuze according to claim 3 in which the rear end of said push-piece is in the form of a sleeve having a frustoconical edge forming said cam means adapted to engage said balls so as to push them inwardly when said push-piece is itself driven rearwardly by impact upon an obstacle.

References Cited in the file of this patent UNITED STATES PATENTS (Addition to No. 779,063) 

